Logon screens

Hello,

A users is logged onto a client's Windows2003 network with a wireless
connection. His OS is Vista Home edition. The network consultant for the
company said he can't authenticate without upgrading his OS. I was however
able to map a drive and bring up two MS Access applications that he needs.
I can't retrace my steps becuase I was just playing around. Can I get a
logon screen to the domain? If so how.

Also, I have another machine which just had Windows 2000 installed and I
need a logon screen for that which asks for a domain. Any help is
appreciated.

Thank you and God Bless,

Mark A. Sma